Not sure how to really tell what mod is causing Zombie Horde to have issues with pollution. But, hopefully the logs and screenshot of the error will help.

Error window: https://i.imgur.com/IgyZZsH.png
Log: https://gist.github.com/skellitor301/5e16538e1b640fa17ac6984010d53939

Yeah a mod must be changing the default enemy pollution absorption. Then that setting is trying to divide by nil.
I see you have a mod enabled called "pollution-as-surface-property" which is a stab in the dark.

Unfortunately I dont have time to look into it, you'll have to disable mods to try and track down the conflict.

So that would be this mod here: https://mods.factorio.com/mod/pollution-as-surface-property Which essentially gives each pollutant a unique ID. This basically allows you to define different pollution types other than the default pollution, like spores, noise, radiation, etc.

Hope this helps narrow it down and potentially makes a fix easy?